Magneto-resistive memory with shared wordline and sense line

Abstract

Methods are disclosed for writing magneto-resistive memory devices. Some of the methods help reduce peak currents during a write, while others increase the speed of the write. To reduce the peak currents, selected control signals such as selected word lines, digital lines and/or sense lines are sequentially activated, rather than activated in parallel. Because the word lines, digital lines and/or sense lines are sequentially activated, the peak currents experienced during a corresponding write may be reduced. To increase the speed of a write, the magnetization vector of the magneto-resistive bits are actively forced to be substantially parallel with the major axis of the magneto-resistive bits, rather than merely drift to that position under the forces inherent in the magneto-resistive bit.

What is claimed is:  
     
       1. A method for writing a magneto-resistive memory, the magneto-resistive memory having a number of magneto-resistive bits organized into a number of words, a number of word lines and a number of digital lines, all of the magneto-resistive bits in a word being selected by a common digital line, and each of the magneto-resistive bits in a word being selected by different word lines, the method comprising the steps of: 
       activating a selected one of the digital lines, which selects all of the magneto-resistive bits in a corresponding word; and  
       sequentially activating the word lines that correspond to selected magneto-resistive bits in the corresponding word.  
     
     
       2. A method according to  claim 1 , wherein the selected digital line is activated during the entire period that the word lines are sequentially activated. 
     
     
       3. A method according to  claim 1 , wherein the activating step activates the selected digital line by providing an activating current to the selected digital line. 
     
     
       4. A method according to  claim 1 , wherein the sequentially activating step sequentially activates the word lines by providing an activating current to the word lines. 
     
     
       5. A method according to  claim 4 , wherein the sequentially activating step provides an activating current in a first direction for those word lines that correspond to magneto-resistive bits that are to be written to a first logic state. 
     
     
       6. A method according to  claim 5 , wherein the sequentially activating step provides an activating current in a second direction for those word lines that correspond to magneto-resistive bits that are to be written to a second logic state. 
     
     
       7. A method according to  claim 1 , wherein the magneto-resistive memory further includes a number of sense lines, wherein all of the magneto-resistive bits in a word are selected by a common sense line. 
     
     
       8. A method according to  claim 7 , further including the step of activating the sense line that selects the magneto-resistive bits of the word that corresponds to the selected digital line. 
     
     
       9. A method for writing a magneto-resistive memory, the magneto-resistive memory having a number of magneto-resistive bits organized into a number of words, a number of word lines and a number of sense lines, all of the magneto-resistive bits in a word being selected by a common sense line, and each of the magneto-resistive bits in a word being selected by different word lines, the method comprising the steps of: 
       activating a selected one of the sense lines, which selects all of the magneto-resistive bits in a corresponding word; and  
       sequentially activating the word lines that correspond to selected magneto-resistive bits in the corresponding word.  
     
     
       10. A method according to  claim 9 , wherein the selected sense line is activated during the entire period that the word lines are sequentially activated. 
     
     
       11. A method according to  claim 9 , wherein the activating step activates the selected sense line by providing an activating current to the selected sense line. 
     
     
       12. A method according to  claim 9 , wherein the sequentially activating step sequentially activates the word lines by providing an activating current to the word lines. 
     
     
       13. A method according to  claim 12 , wherein the sequentially activating step provides an activating current in a first direction for those word lines that correspond to magneto-resistive bits that are to be written to a first logic state. 
     
     
       14. A method according to  claim 13 , wherein the sequentially activating step provides an activating current in a second direction for those word lines that correspond to magneto-resistive bits that are to be written to a second logic state. 
     
     
       15. A method according to  claim 9 , wherein the magneto-resistive memory further includes a number of digital lines, wherein all of the magneto-resistive bits in a word are selected by a common digital line. 
     
     
       16. A method according to  claim 15 , further including the step of activating the digital line that selects the magneto-resistive bits of the word that corresponds to the selected sense line. 
     
     
       17. A method for writing a magneto-resistive memory, the magneto-resistive memory having a number of magneto-resistive bits organized into a number of words, a number of word lines and a number of digital lines, all of the magneto-resistive bits in a word being selected by a common word line, and each of the magneto-resistive bits in a word being selected by different digital lines, the method comprising the steps of: 
       activating a selected one of the word lines, which selects all of the magneto-resistive bits in a corresponding word; and  
       sequentially activating the digital lines that correspond to selected magneto-resistive bits in the corresponding word.  
     
     
       18. A method according to  claim 17 , wherein the selected word line is activated during the entire period that the selected digital lines are sequentially activated. 
     
     
       19. A method according to  claim 17 , wherein the activating step activates the selected word line by providing an activating current to the selected word line. 
     
     
       20. A method according to  claim 19 , wherein the sequentially activating step sequentially activates the digital lines by providing an activating current to the selected digital lines. 
     
     
       21. A method for writing a magneto-resistive memory, the magneto-resistive memory having a number of magneto-resistive bits organized into a number of words, a number of word lines and a number of sense lines, all of the magneto-resistive bits in a word being selected by a common word line, and each of the magneto-resistive bits in a word being selected by different sense lines, the method comprising the steps of: 
       activating a selected one of the word lines, which selects all of the magneto-resistive bits in a corresponding word; and  
       sequentially activating the sense lines that correspond to selected magneto-resistive bits in the corresponding word.  
     
     
       22. A method according to  claim 21 , wherein the selected word line is activated during the entire period that the selected sense lines are sequentially activated. 
     
     
       23. A method according to  claim 21 , wherein the activating step activates the selected word line by providing an activating current to the selected word line. 
     
     
       24. A method according to  claim 23 , wherein the sequentially activating step sequentially activates the sense lines by providing an activating current to the selected sense lines. 
     
     
       25. A method for writing a magneto-resistive memory, the magneto-resistive memory having a number of magneto-resistive bits organized into a number of words, a number of word lines and a number of digital lines, all of the magneto-resistive bits in a word being selected by a common word line, and each of the magneto-resistive bits in a word being selected by different digital lines, the method comprising the steps of: 
       providing a current in a first direction to a selected one of the word lines, which selects all of the magneto-resistive bits in a corresponding word;  
       sequentially activating a first subset of those digital lines that correspond to selected magneto-resistive bits in the corresponding word, the first subset of digital lines corresponding to those magneto-resistive bits that are to be written to a first logic state;  
       providing a current in a second direction to the selected word line; and  
       sequentially activating a second subset of those digital lines that correspond to the selected magneto-resistive bits in the corresponding word, the second subset of digital lines corresponding to those magneto-resistive bits that are to be written to a second logic state.  
     
     
       26. A method according to  claim 25 , wherein the magneto-resistive memory further includes a number of sense lines, wherein all of the magneto-resistive bits in a word are selected by a common sense line. 
     
     
       27. A method according to  claim 26 , further including the step of activating the sense lines that correspond to the magneto-resistive bits in the corresponding word. 
     
     
       28. A method according to  claim 26 , further including the steps of 
       sequentially activating a first subset of those sense lines that correspond to the selected magneto-resistive bits in the corresponding word, the first subset of sense lines corresponding to those magneto-resistive bits that are to be written to the first logic state; and  
       sequentially activating a second subset of those sense lines that correspond to the selected magneto-resistive bits in the corresponding word, the second subset of sense lines corresponding to those magneto-resistive bits that are to be written to the second logic state.  
     
     
       29. A method for writing a magneto-resistive memory element, the magneto-resistive memory element having a word line and a digital line extending adjacent a magneto-resistive bit, the method comprising the steps of: 
       providing a current to the word line;  
       providing a current to the digital line; and  
       removing the current to the digital line before removing the current to the word line.  
     
     
       30. A method according to  claim 29 , wherein the magneto-resistive bit is included in a sense line, the method further comprising the steps of: 
       providing a current to the sense line; and  
       removing the current to the sense line before removing the current to the word line.  
     
     
       31. A method for writing a magneto-resistive memory element, the magneto-resistive memory element having a word line extending adjacent a magneto-resistive bit, and the magneto-resistive bit being included in a sense line, the method comprising the steps of: 
       providing a current to the word line;  
       providing a current to the sense line; and  
       removing the current to the sense line before removing the current to the word line.